I. Field of the Invention
The present invention is directed generally to portable diagnostic or electro-analytical systems that make in vitro electrochemical determinations based on fluid biological samples extracted from patients and characteristically analyzed for concentrations of specific electroactive species. The system employs a cartridge containing a bank of sensors for the pertinent electroactive species which provide input in the form of analog electrical signals for the relevant determinations. More particularly, the instant invention is concerned with a portable diagnostic or analytical instrument that interfaces and uses cartridges selected from single-use cartridges interchangeably with a modular multiple-use cartridge system to make rapid, accurate point-of-care determinations at low cost and requiring only a relatively low skill level to operate successfully.
II. Related Art
The measurement of certain physical/chemical characteristics or conditions of the blood can be quite important with respect to evaluating the condition of a patient in a variety of clinical situations. The partial pressures of O.sub.2 and CO.sub.2, pH, together with the measurement of certain ions, such as Ca.sup.++ and/or K.sup.+, provide important indications of the efficiency of the blood/gas exchange occurring in the lungs of the patient, relative acid/base balance in the concentration of certain indicative ion species in the blood, respectively. Hematocrit is also an important determination. These measurements are particularly critical in life-threatening circumstances.
While formerly all such analyzers of the class employed to make such determinations were costly, permanently installed devices in the hospital laboratories which required highly-trained, skilled technicians to operate them. More recently, portable units have become available which make fairly rapid analyses in the operating room, such as during open heart surgery, the intensive care unit and the emergency room. In these areas, of course, immediate diagnostic and therapeutic decisions are often required. The data from blood gas, electrolyte and certain other tests forms the basis for such reactions.
Systems are also available which utilize a plurality of cartridge-mounted sensors to sequentially make many sample determinations. Examples of such systems are shown in U.S. Pat. Nos. 4,786,394 and 4,871,439 to Enzer et al and, more recently, reusable, multiple sample testing systems are shown in European Patent Application 0 520 443 A2 to Betts et al. and in certain Mallinckrodt product information material dated 1993-1995. Thus, while single-use and multiple-use systems exist, the per test cost has remained relatively high in comparison with laboratory systems and the versatility associated with the ability to accommodate both single-use and multi-use cartridges interchangeably as heretofore not been available.
Accordingly, it is a primary object of the present invention to provide a portable, point-of-care analytical system that interchangeably accommodates single-use cartridges and a multi-use cartridge module.
Another object of the present invention is to provide a portable point-of-care analytical instrument that accommodates both single-use cartridges and a multi-use cartridge test module interchangeably without modification.
Yet another object of the present invention is to provide a plug-in multi-use sensor cartridge module for a portable, point-of-care blood analysis instrument which uses no more power than a single-use cartridge.
Other objects and advantages of the present invention will become apparent to those skilled in the art upon familiarization with the specification, drawings and claims contained herein.